LED replacement for standard halogen headlights?

Conventional bulbs has a incandescent wire which has to be hot to emit light (like fire). They are hot all time.
While LED are emits light in different way, but there is a current limit, where LEDs begin to produce heat, and less light, efficiency falling dramatically.

But the technology evolving fast in 2006 demostrated a 131 lm/W at 20 mA diode, and they going for 150 lm/W. (standard bulbs has 15 lm/W efficiency).

The problem is not with the brightness, but with focusing the light, cause they emmits the light differently (many tiny sources), than halogens.

Anyway, my 06 prius has combo H4 halogens, so the replacement more difficult (is any).

 

Those of us in Canada all got halogens due to us running them at low power in the day as DRLs. Can diode lights be turned to a lower output, or is there only one output level, like the HIDs?

 

LEDs are indeed more efficient and produce less heat for the same light output. The problem is how and where the heat is produced. Normal incandescent lights radiate most of the heat away, which is why they feel like heat lamps when you get close to them. LEDs, on the other hand, generate a smaller amount of heat, but it's all concentrated at the semiconductor junction. The junction is very small and not a good radiator of heat, so a large heat sink is required to keep the LED from overheating. Overheating will quickly destroy a semiconductor.

The need for a heat sink is one of the primary problems involved with retrofitting LEDs into normal light fixtures. It's much easier to accommodate the heat sink requirement with a purpose designed fixture. That's not to say that retrofit LEDs will never work, but it is more difficult to do it correctly, even ignoring the obvious difference in beam pattern.

Tom

 

99% of LED's for sale (for example) as R30 can light replacements as well as other applications at your local Home Depot or WalMart state right on the box, "NOT designed for use in 3 way or dimmer applications". So ... how does one reconcile that, along with the idea that LED brightness can be controlled very easily/efficiently?

Changing the subject slightly, there's a video here on PC showing the HUGE amount of talent/energy/grief/patience needed to take apart a Prius HID headlight for element replacement. Hats off, if you got the time to do all that.
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LED brightness is normally controlled with a pulse width modulator (PWM) dimmer circuit. This is because LEDs don't conduct until they reach some critical voltage. A PMW circuit runs the LEDs at full voltage, but for only a percentage of the time.

Cheap LED replacement lamps only draw power for a short blip on each AC cycle, close to the maximum voltage at the top of the sine wave.

The simple dimmers used for normal lights are thyristor controllers that work by controlling the turn on phase angle on the AC waveform. This doesn't work well with cheap replacement LEDs because they are only conducting for a short blip anyway. The dimmer varies how much of the AC waveform the LEDs see, but it doesn't make any difference to the brightness.

To really work well, the LED drivers need to convert the AC to DC and then do PWM control. Some of the better units do this, and can respond to normal dimmers, but it takes a lot of extra circuitry to make the LEDs backward compatible.

Tom

 

Those are a decorative item and would be awful for actual driving.

All of the HID family are On/Off by nature. If you underdrive them they won't start. Incandescent (such as Halogen)and LED can be driven harder or softer to make them brighter or dimmer.

The problem is in the circuitry that drives it, not the LED itself. Most of the LED lights you see in a store are cheap Chinese junk. They don't deserve to be in your house. Those guys won't spend an extra nickel on the design if they can avoid it. This means you get a product that dies if you look at it funny. If you do buy one keep the receipt and packaging (package normally has claimed life expectancy written on it) and write on the bulb the date it goes into service.

Linkey?

 

Now that it is 6.5 years later, does anyone know of reputable LED replacement headlight bulbs for a 2006 Prius?

 

SuperBrightLEDs has LED headlight bulbs that are powerful enough to be used as headlights. Their color temperature may be too cool for some people's taste. The light pattern may be questionable in some housings. The only way to know is ask someone who has tried, or try them yourself. I put H4 LEDs in my '94 Miata, the pattern was unusable. In other housings, like the Prius, they may work.

Semi related, I put LEDs from SuperBrightLEDs in my fog lights on my 2008, they work great. Got the ones with the passive fixed heatsink, not the flexible heatsink or fan heatsink.

 

I'd be curious about these. Should be able to handle even the low 9v DRL wattage. Pretty bright...i'm sure the light scatter would be just as bad as HID in halogen housings....definitely not optimal for oncoming traffic.



2pcs 90W H4 Hi Lo 11000LM LED CREE ETI LED Headlight Kit Bulb Xenon White Lamp | eBay

 

I installed LED headlights about a year ago, replacing the halogens. I'm happy with them. They are very bright. At first a lot of drivers flashed at me so I aimed them further down.

I bought them from AliExpress for about $45 (for 2 bulbs). The exact listing seems to be gone ("40W H4 LED headlight bulb cree led conversion kit") but there are other ones. DRL function works ok for me here in Canada. The bulbs have a small fan and heatsink to keep them cool. Cheaper than many of the replacement halogens available.